Plastic closure for paper containers and metho of making same

ABSTRACT

The present invention relates to a container such as a paper envelope having an access closed by a flap releasably held closed by plastic snaps comprising a first snap element securely bonded to the body of the envelope, and a second snap element securely bonded to the flap, said first and second snaps adapted to releasably attach to each other, with the snap elements each being directly bonded to the paper-like material, and formed for combined strength and efficiency of space. The invention also provides a method of making a plastic closure system directly on a paper envelope having a main body section and a closure portion, which comprises molding a thermoplastic element directly adjacent to the main body and bonded therewith during formation thereof, and molding a second and mating closure element on the closure portion by direct molding with a thermoplastic material and in contact with said closure portion.

United States Patent 11 1 Wiseman 1451 Aug. 7, 1973 [76] Inventor:Robert F. Wiseman, 1227 Anza, San

Francisco, Calif. 941 18 [22] Filed: Jan. 13, 1971 [21] Appl. No.:106,134

Germany 24/208 R Primary Examiner-Richard A. Schacher Att0rney-Schapp &Hatch [57] ABSTRACT The present invention relates to a container such asa paper envelope having an access closed by a flap releasably heldclosed by plastic snaps comprising a first snap element securely bondedto the body of the envelope, and a second snap element securely bondedto the flap, said first and second snaps adapted to releasably attach toeach other, with the snap elements each being directly bonded to thepaper-like material, and formed for combined strength and efficiency ofspace. The invention also provides a method of making a plastic closuresystem directly on a paper envelope having a main body section and aclosure portion, which comprises molding a thermoplastic elementdirectly adjacent to the main body and bonded therewith during formationthereof, and molding a second and mating closure ele ment on the closureportion by direct molding with a thermoplastic material and in contactwith said closure portion.

6 Claims, 8 Drawing Figures PLASTIC CLOSURE FOR PARER CONTAINERS ANDMETHO OF MAKING SAME BACKGROUND OF THE INVENTION The present inventionrelates to a PLASTIC CLO- SURE FOR PAPER CONTAINERS AND METHOD OF MAKINGSAME, and more particularly to such a construction where the plasticclosure elements are made from thermoplastic resinous material.

It is well known to provide containers and envelopes made from paper orcardboard, and where an envelope is to be used once and then discarded,it may be sealed by any suitable means and torn open for use. However,where it is desired to use the envelope over a period of time and haveaccess to material contained therein, it is necessary to either leavethe envelope unsecured or to provide a temporary closure system whichmay be opened and closed as desired. It is this letter type of closureto which the invention is directed.

One of the most frequently used envelopes of the class describedcontains a metal fastener, which is punched through, secured to the mainbody of the paper, and adapted to have a pair of bendable prongs extendthrough a reinforced hole in a flat portion thereof. While theseclosures are eminently suited for the purpose, certain disadvantageshave been encountered, particularly in the cost of fabrication thereof.First of all, in order to punch the fastener to the envelope it isnecessary for the machine to separate the two adjacent sheet portions sothat the metal element may be punched through and secured withoutfastening the entire envelope in a closed relation. In addition, it isnecessary to reinforce the hole so that this closure will retain theenvelope in a closed position rather than causing the flap to tear away.The difficulties encountered in securing the fastener are such that itrequires a costly machine, and even with costly machines breakdownsfrequently occur.

Another problem that has been encountered with envelopes of this kindresides in the fact that after a limited use the metal prongs break.This is caused by the necessary bending of their metal during theopening and closing operation. Efforts to solve such problems haveheretofore lead to more expensive and more bulky elements such as thestring closures now in use.

The use of snap elements on envelopes tends to render the device moresuitable for large numbers of opening and closing operations, butheretofore snap elements were difficult or expensive to apply to theenvelope. These problems are overcome by the method aspect of thepresent application. In addition, the present invention also providesfor an improved plastic closure element having certain advantages thatwill be apparent as the specification progresses.

SUMMARY OF THE INVENTION From the above description it is seen that aprimary object of the invention is to provide a closure for paperlikeenvelopes or the like which is simple and inexpen sive to fabricate andcapable of heavy usage over a considerable length of time.

Snap elements have been conventionally applied to cellulosic textilematerials by sewing and the like, and this is true even with plasticsnap elements. Another method of attachment resides is providing keepers that are permanently secured to grip a portion of the material andretain the fastener in place. Such systems are suitable for relativelystrong textile materials, but are not satisfactory for securing'thefasteners to paper materials.

Due to the advent of superior adhesive materials, it is possible tosecure plastic snap elements to paper and the like by using suchadhesives. However, the placement of adhesive on individual snapelements and the location of the elements on the envelopes is arelatively costly operation. These problems are overcome by applicantsmethod of molding the snap element in place so as to form the element incontact with the cellulosic material, and obtain adherence by utilizingcertain of the socalled hot melt thermoplastic materials for moldingthat are capable of adhering to paper when heated to the plastic state.

Practically all of the thermoplastic materials which are capable ofbeing softened without decomposition and cast could be used to form snapelements adjacent to the paper product. However, it has been found thatmaterials such as polyethylene and related polyolefins, which do notcontain polar groups generally do not provide the desired adherence topaper products. However, thermoplastic materials having sufficient polargroups thereon to bond with the paper form excellent adhesivecharacteristics so that when the snap element is formed adjacent to thepaper, it cannot be removed withouttearing off at least a surface layerof the paper withit. Accordingly, the securin gefiect is as strong asthe paper itself. This is true of certain oxygenated thermoplasic resinssuch as vinyl acetate copolymers, and a preferred plastic is a typicalcommercially available copolymer of ethylene and vinyl acetate sold as ahot melt. i

In addition to thermoplastic resins with polar groups, thermoplasticmaterials containing an adhesive ingredient as a physical componenttherein may be used. Many such hot melt items are readily available onthe market, and the adhesive properties are well known in the plasticart. Accordingly, many materials are available which have the desiredphysical properties. i

In order to utilize the typical hot melt" materials available on themarket, it is preferred to utilize the special pair of molds which maybe attached to a typical envelope machine so as to mold the desiredfastening elements in position, rather than attach an element as nowaccomplished by such machines. Accordingly, a relatively simplemodification of present machinery is possible, because the handling ofthe envelopes during application of the closure elements would be thesimilar. In other words, the machines are modified by the addition of asuitable molding device, which will cast on the adhesive to the paperenvelope in the desired places to form the desired fastening elements.Although a typical fastening system would involve two elements such as amale and female snap element, it will be appreciated that more than onepair of such elements may be provided if desired. It will also beappreciated that various forms of securing elements may be utilized suchas letters or simple trademark symbols, if desired.

In its method form, the plastic is heated and applied through a typicalmelting machine such as devices utilized for spraying hot melt or thelike and passed down into a molding head which in turn is placedadjacent to the envelope. A desired amount of hot plastic is meteredthrough the mold, the mold stamped down so as to form the snap elementfirmly on the paper, and then the mold is then pushed away from thepaper preferably by a self-yielding system such as springs to clear themold from the device. By selecting the proper temperatures of the moldand hot melt, the snap element will set up almost immediately uponremoval, but settle in a little as it cools to form a sufficiently tightsnap pocket prior to final hardening.

The hot metal material should not only adhere to the paper, but itpreferably should have a sufficiently high melting point that it willnot become tacky under using conditions and may be readily separated asdesired with snap elements. If desired, a suitable powder may be appliedover the molded product immediately after formation in order to providea more suitable non-sticky surface.

From the above description, it is seen that snap elements may be moldeddirectly to the paper and thus provide a new article of manufacture,namely an envelope-like construction containing snap elements directlybonded to the flat surfaces thereof. In addition, the snap elements mayassume any desired configuration, and the preferred form of theinvention utilizes snap elements having reinforcement sections so as toprotect the edge of the flap of the envelope from tearing use. Ifdesired, a tab may be placed on the snap element to'provide an elementto assist in opening the snaps. Accordingly, certain preferred closurestructures are also provided by the present invention.

It is also desired to utilize snap elements that are comparatively thinand have very little base thickness. This is made possible by the factthat the snap becomes integral with the envelope and the envelope paperin effect can become part of the snap body. By making snaps relativelythin (i.e., having a thin floor section), an envelope is provided whichis more readily stored than one that would contain conventional snapelements thereon. From the above description, it is seen that anotherobject of the invention is to provide an improved envelope having a.special snap closure construction formed therewith.

A further object of the invention is to provide a method ofmanufacturing envelopes or the like having closure elements thereonutilizing envelope handling machinery somewhat similar to that now inuse, but modified to provide an improved construction.

Further objects and advantages of the invention will be apparent as thespecification proceeds and the new and useful features of the plasticclosure for paper container and method of making same will be more fullydefined in the claims attached hereto.

BRIEF DESCRIPTION OF THE DRAWING The preferred forms of the inventionare illustrated in the accompanying drawing, forming a part of thisdescription, in which:

FIG. 1 is a perspective view of a typical envelope constructed accordingto the invention;

FIG. 2, an enlarged fragmentary view of the envelope as seen in FIG. 1;FIG. 3, an enlarged, fragmentary, cross-sectional view of the envelopethrough the fastening means illustrating the construction of thefasteners in the open position;

FIG. 4, a view similar to that shown in FIG. 3, but illustrating thefasteners in a closed position;

FIG. 5, a plan view, partly in cross-section, illustrating a typicalmold that may be utilized to carry out the method aspect of theinvention;

FIG. 6, an envelope similar to that shown in FIG. 1, illustrating amodified form of the invention;

FIG. 7, a view similar to that shown in FIG. 6, but illustrating stillanother embodiment of the invention; and

FIG. 8, a perspective view illustrating yet another modification of theinvention.

While only the preferred forms of the invention are shown and describedin detail, it should be understood that various changes or modificationsmay be made within the scope of the claims attached hereto withoutdeparting from the spirit of the invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring to the drawing ingreater detail and particularly to FIGS. 1 through 4, there is shown anenvelope 11 formed in a typical flat arrangement with a pair of flatbody members enclosing a space therebetween by virtue of having threeclosed sides, and a flap 12 adapted to fold over the main body 13 forcompleting the closure. As used herein, the term envelope is construedto mean any container capable of providing a complete enclosure andincludes the box-like configuration shown in FIG. 8 as well as thepreferred folded flat form shown in FIG. 1. However, the envelopes ofthis invention are composed of non-woven cellulosic material typicallyformed into paper or cardboard. Such envelopes have the advantage ofbeing inexpensive and enjoy widespread usage because of their practicaladvantages.

Rererriagtigaifi to FIGS.'Ithrouglil'tliere is shown a pair of snapelements 14 and 16, with snap element 14 being located on flap 12 andsnap element 16 being located on the main body 13. As shown herein, thefemale element 14 is located on the flap and the male element 16 islocated on the main body of the envelope, but it will be appreciatedthat the parts may be re versed, if desired, without departing from thespirit of the invention.

Referring more particularly to FIGS. 3 and 4, it is seen that snapelements 14 and 16 are each directly bonded to the paper without use ofadhesive or otherwise. As shown in the drawings, an extending coating orfloor portion 17 and 18 is provided on each of the snap elements inorder to provide a stronger attach ment and reinforce the strength ofthe paper at the position of the fastener.'Preferably, this portion ismade relatively thin as are the connecting elements 19 and 21 in orderto prevent undue thickness in the snap elements. However, male element19 and female element 21 should be large enough to provide the desiredsecuring forces. Although a typical circular snap form is here shown, itwill be appreciated that the form the snap element takes may vary inaccordance with design desires, and circular shape shown is forillustration only.

In its method form, the invention comprises the steps of providing andheating a thermoplastic material above the softening point and to itsplastic state, preferably to the state of hot melt as is well known inthe art. Applying the plastic in the hot melt form through a typicaldelivery apparatus such as the apparatus 22 which is formed to deliver aspray-like liquid of thermoplastic material when a nozzle is positionedin place of the typical mold element 23 as shown in FIG. 5. The softenedthermoplastic material is then formed onto sheet 12 as shown in FIG. 5,the mold element 23 retracted, and formation of a snap element 14 iscompleted.

Referring more particularly to the apparatus shown in FIG. 5, a sprayhead for delivery of liquid resin is available commercially and providesa passageway 24 for discharging melted resin at a controlledtemperature. The machine is modified by providing a mold element 23,which is held in place by bushing 26. The bushing 26 is also formed toprovide a stop and retain skirt 27 from coming off the mold. Skirt 27 isurged outwardly toward the stop by compression spring 28, and thisaction is used to normally retract the mold from sheet 12.

In operation, the mold 22 is pushed downward so that skirt 27 firstmoves against the sheet 12 in the desired location, a metered amount ofheated plastic is then supplied through passage 24, the mold is thendepressed to form an element such as element 14, and the mold is allowedto retract by action of spring 28 to separate the mold from the snapelement formed on the paper. If desired, the entire mold configurationmay be made in mold element 23, or the outer portion of the mold elementmay be a portion of bushing 26 so as to allow the mold area to reach thearea defined by skirt 27.

It will be appreciated, that machines presently. set up to handleenvelopes and place metal fasteners and reinforcing rings thereon mayhave suitable molds substituted at the proper location and utilized forproviding snap elements on the envelope in accordance with the presentinvention. It will Also be appreciated that the mold elements may bemade interchangeable so that different designs of snap elements may beprovided from substantially the same machines, with only minor changesnecessary. Certain different embodiments of snap elements areillustrated in FIGS. 6 through 8, where certain constructionaladvantages are also provided.

Thus, referring now to FIG. 6, there is shown an envelope 11a having apair of snap elements 14a and 16a with the snap element 14a beingprovided with a tab portion 31. This tab 31 is utilized to enable theuser to obtain a more ready grip on the snap for opening same.

In FIG. 7, there is shown another modified envelope 11b equipped withsnap elements 14b and 16b. Snap element 14b has its floor section 17bthereof extending to the edge of the flap near the fastener fromtearing.

In FIG. 8, there is shown an envelope 11c in the form having the abilityto bond with paper, with each snap of a box-like configuration, with theflap 12c being equipped with the snap element similar to snap element 14of FIG. 1, while the body portion 13c is a snap element 16c similar tothe snap element 16 of FIG. 1. It will also be appreciated that otherdesign modifications may be made, if desired, but it is believed thatthose modifications shown are illustrative of the various forms ofpaperlike containers utilized in the present invention.

From the above description, it is seen that I have provided a novelplastic snap which is directly mounted to a paper-like container toprovide an improved temporarily closable envelope, and that I haveprovided a new and useful method of makiuG same.

I claim: I

1. In a paper envelope having a main body and a flap member, incombination; a plastic closure means, comprising a first snap elementsecurely bonded directly to the body of the envelope, and a second snapelement securely bonded directly to the flap member of the envelope andadapted to releaseably attach to said first snap element, said snapelements each being formed substantially in their entirety of thethermoplastic resin element being directly heat bonded to the envelope.

2. A paper envelope as defined in claim 1, in which each element isformed with a thin floor section for providing secure attachment to the:paper, and in which the thickness of each snap element is minimal,whereby flat envelopes may be stacked in close proximity to each other.

3. A paper envelope as defined in claim 2, in which the floor portion ofthe second element has an edge corresponding with the edge of the flapfor a distance substantially the width of the snap element for providingreinforcement in the area of strain during opening of the snap.

4. A paper envelope as defined in claim 1, in which a tab is formed ofthermoplastic material, with said tab being provided on the second snapelement for use in opening the snaps.

5. A paper envelope as defined in claim 1, in which the envelope is offlat configuration with the main body portion comprising two sheets ofpaper in face-to-face orientation, and in which the edges of the snapelements are tapered at their line of juncture with the paper.

6. A paper envelope as defined in claim 1, in which the envelope is of abox-like configuration.

1. In a paper envelope having a main body and a flap member, incombination; a plastic closure means, comprising a first snap elementsecurely bonded directly to the body of the envelope, and a second snapelement securely bonded directly to the flap member of the envelope andadapted to releaseably attach to said first snap element, said snapelements each being formed substantially in their entirety of thethermoplastic resin having the ability to bond with paper, with eachsnap element being directly heat bonded to the envelope.
 2. A paperenvelope as defined in claim 1, in which each element is formed with athin floor section for providing secure attachment to the paper, and inwhich the thickness of each snap element is minimal, whereby flatenvelopes may be stacked in close proximity to each other.
 3. A paperenvelope as defined in claim 2, in which the floor portion of the secondelement has an edge corresponding with the edge of the flap for adistance substantially the width of the snap element for providingreinforcement in the area of strain during opening of the snap.
 4. Apaper envelope as defined in claim 1, in which a tab is formed ofthermoplastic material, with said tab being provided on the second snapelement for use in opening the snaps.
 5. A paper envelope as defined inclaim 1, in which the envelope is of flat configuration with the mainbody portion comprising two sheets of paper in face-to-face orientation,and in which the edges of the snap elements are tapered at their line ofjuncture with the paper.
 6. A paper envelope as defined in claim 1, inwhich the envelope is of a box-like configuration.